Recently, there has been a rapid increase in the transmission and/or storage of image information and the like. This has been especially true in the use of facsimile. Additionally, use of high resolution monitors for generating a soft copy and/or browsing of the image information has resulted in additional requirements being placed on digital transmission and/or storage interfaces. In certain applications, rapid progression from a low resolution replica to a high resolution image is desirable and sometimes necessary. In order to improve encoding/decoding efficiency and speed, prior arrangements were employed which decomposed a high resolution image into a lower resolution replica and so-called supplemental information. The supplemental information was required to later recompose the low resolution replica into the high resolution image. In one known prior arrangement, supplemental information was generated only for pixels (picture elements) determined to be at a so-called "edge" in a resulting low resolution replica. Pixels not originally determined to be at an edge in the low resolution replica that were determined to require supplemental information were forced to be at an edge by modifying the image reduction rules. That is, the reduction rules were modified to force a pixel to be at an edge in the low resolution replica whenever the prediction rules would cause a decoder to otherwise improperly recompose the high resolution image. See, for example, our co-pending U.S. patent application Ser. No. 146,998, filed Jan. 22, 1988 now U.S. Pat. No. 4,870,497 issued Sept. 26, 1989 for one such prior arrangement.
A serious limitation of such a prior arrangement is that the prediction rules used to determine if supplemental information was required to be generated and encoded were based and dependent on the particular properties of the image reduction rules. Therefore, if the image reduction rules were changed, the prior prediction rules could not be used. Thus, any change in the image reduction rules would require development of a new set of prediction rules. This interdependence of the image reduction rules and the prediction rules is undesirable.